The invention relates to improvements in methods of and in means for compensating for the influence of rotational speed upon the control torque characteristic curve of a clutch, such as the friction clutch between the prime mover and the change-speed transmission in the power train of a motor vehicle.
It is becoming customary to equip the power trains of motor vehicles with automated clutches, especially electronically operated clutches which are actuated by control units equipped with microprocessors having information storing facilities. Such clutches contribute not only to the comfort of operation but also to a reduction of fuel consumption, especially when they are called upon to transmit torque to automated transmissions.
An important parameter for the operation and/or controlling of automatic clutches is the so-called control torque characteristic curve which determines the desired or required path for an adjusting member in dependency upon the torque, especially slip torque, which is to be transmitted by the clutch. Such characteristic curve, also known as setting torque characteristic curve, changes gradually during the life span of the clutch, e.g., as a result of wear and/or similar influences; in order to compensate for such gradual influences, the clutch is monitored automatically at predetermined operating points and is actualized or adapted accordingly.
A short-lasting change of the control torque characteristic curve, for example, a change lasting only a few seconds, is not likely to be detected by the control system for the clutch. This can cause serious problems because numerous clutches are highly likely or bound to develop changes of their control torque characteristic curves, for example, changes which are attributable to changes of rotational speed of a rotary part of the clutch. Failure to detect changes of characteristic curve can result in unsatisfactory operation of the clutch and can adversely affect the comfort of the operator of and/or passenger(s) in the motor vehicle during shifting of the transmission into different speeds but particularly during setting of the motor vehicle into motion.